£1.00 – £2.74
Biotite granite igneous rock specimens from Ballachulish, Scotland, UK. Composed of the felsic minerals quartz and feldspar, with occurrences of biotite crystals. The rock has an overall white appearance due to its felsic chemistry but the black biotite mica offers a striking contrast in colours. The samples are ideal for both collectors due to the attractive nature and for college to university level education to describe the variations in granite which one may find. The samples are available in three sizes and supplied in a card tray with an information label.
Biotite granite is a coarse grained intrusive igneous rock of felsic chemistry, as the name and chemistry suggests, this variant of granite is composed mainly of the minerals quartz, feldspar with biotite mica. The quartz present in the rock is a white colour due to the presence of fluids as gas inclusions during the time the rock formed. Plagioclase feldspar, a sodium mineral, which is typically white in colour because of the presence of albite or anorthite give the rock an overall white or very pale grey colouration. However, the presence of biotite mica crystals within the rock give it a striking appearance due to the complete contrast in opposite colours making this rock not only sought after by collectors but also often used in various masonary, decorative and building use due to it's attractive appearance. This rock comes from Ballachulish, Scotland in the UK and is an excellent rock for educational use to describe the variations of granite which can be found. The samples are available in three sizes and come supplied in a card tray with a label.